package chapter2;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

/**
 * Basic IO example with CTR using AES
 */
public class SimpleIOExample {
	public static void main(String[] args) throws Exception {
		Security.addProvider(new BouncyCastleProvider());
		byte[] input = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
				0x0e, 0x0f, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 };
		byte[] keyBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c,
				0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17 };
		byte[] ivBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
				0x00, 0x00, 0x01 };

		SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
		IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
		Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC");

		System.out.println("input : " + Utils.toHex(input));

		// encryption pass

		cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);

		ByteArrayInputStream bIn = new ByteArrayInputStream(input);
		CipherInputStream cIn = new CipherInputStream(bIn, cipher);
		ByteArrayOutputStream bOut = new ByteArrayOutputStream();

		int ch;
		while ((ch = cIn.read()) >= 0) {
			bOut.write(ch);
		}

		byte[] cipherText = bOut.toByteArray();

		System.out.println("cipher: " + Utils.toHex(cipherText));

		// decryption pass

		cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);

		bOut = new ByteArrayOutputStream();

		CipherOutputStream cOut = new CipherOutputStream(bOut, cipher);

		cOut.write(cipherText);

		cOut.close();

		System.out.println("plain : " + Utils.toHex(bOut.toByteArray()));
	}
}
